A brake system can be used to slow or stop a moving vehicle. Brake systems typically include a brake caliper, inboard and outboard brake pads, and one or more brake pistons. During application of the brake system, the one or more brake pistons are moved, which causes the brake pads to move into contact with a brake rotor to create a clamping force to slow or stop the vehicle.
Some brake systems also include electromechanical parking brake systems to prevent movement of a stopped or parked vehicle. Some parking brake systems include one or more rotary to linear stage mechanisms that function to convert an input torque into a linear force to move the one or more brake pistons and brake pads into contact with the brake rotor to create the clamping force necessary to prevent movement of the vehicle.
Over time, brake pads tend to wear unevenly, producing a condition known as taper wear, where the leading end of the brake pad wears more than the trailing end of the brake pad. As a result, the leading end of the brake pad moves closer to the brake rotor compared to the trailing end of the brake pad. When taper wear occurs in brake systems having two or more brake pistons, the brake piston located at the leading end of the brake pad typically automatically adjusts its position relative to the brake pad during application of the service brake by moving out of the caliper bore and closer to the leading end of the brake pad that has moved closer to the brake rotor so that the brake system can remain responsive during successive applications of the service brake.
However, parking brake systems that are incorporated into brake systems having two or more brake pistons typically do not automatically adjust to compensate for brake pad wear during application of the service brake. Instead, some parking brake systems are adapted to make adjustments for pad wear or taper wear after the parking brake system has been applied. However, if a parking brake system is used infrequently, and/or if the brake pad has worn substantially since the last application of the parking brake, more time may be required to move the elements of the parking brake system to generate the clamping force necessary to maintain the vehicle in a stopped or parked position.
It may therefore be desirable to have a parking brake system that can automatically adjust during application of the service brake or during a brake apply to compensate for brake pad wear or taper wear so that when the parking brake is applied, a clamping force can be quickly and sufficiently.